Automatic sortation system control



R. F. PURNELL AUTOMATIC SORTATION SYSTEM CONTROL Sept. 19, 1961 8 Sheets-Sheet 1 Filed Sept. 25, 1958 NGK.

8 Sheets-Sheet 2 R. F. PURNELL AUTOMATIC SORTATION SYSTEM CONTROL f'fs. 2.

\ V4-aa Sept. 19, 1961 R. F. PURNELL 3,000,519

l AUTOMATIC soRTATIoN SYSTEM CONTROL Filed Sept. 23, 1958 8 Sheets-Sheet 3 Sept. 19, 1961 R. F. PURNELL 3,000,519

i AUTOMATIC soRTATToN SYSTEM CONTROL Filed Sept. 23, 1958 8 Sheets-Sheet. 4

Sept. 19, 1961 R. F. PURNELL AUTOMATIC SORTATION SYSTEM CONTROL 8 Sheets-Sheet 5 Filed Sept. 25, 1958 R. F. PURNELL AUTOMATIC SORTATION SYSTEM CONTROL sept.. 19, 1961 Filed sept. 2s, 1958 8 Sheets-Sheet 6 Sept. 19, 1961 R. F. PURNELL 3,000,519

AUTOMATIC soRTATToN SYSTEM CONTROL- @Vin/701? @fc/afa', {paws/ @WQ/5w@ Sept. 19, 1961 R. F. PURNELL. 3,000,519

AUTOMATIC SORTATTON SYSTEM CONTROL Filed Sept. 23, 1958 8 Sheets-Sheet 8 United States Patent Ol 3,000,519 AUTOMATIC SORTATION SYSTEM CONTROL Richard F. Purnell, Hinsdale, Ill., assigner to Stewart- Warner Corporation, Chicago, lll., a corporation of Virginia Filed Sept. 23, 1958, Ser. No. 762,782 21 Claims. (Cl. 214-11) The present invention relates to systems for automatically controlling the sortation of objects and more particularly to an automatic conveyor control system.

During the past decade, we have seen the value of human labor steadily rise. As a consequence of this, labor costs have also beenincreasing at a steady rate. This increase has been even -rnore noticeable in the area of lunskilled labor ofthe type used in various handling `and sorting operations. Industries which employa large staff of personnel working primarily in handling and'sorting are looking to automatic means to ease their ,burden from a iinancial standpoint. Automatic sorting, where packages are discharged automatically intoY groups according to their selected destination, is becoming financially lfeasible in a steadily increasing number of applications as each year passes. f

An examination of automatic sortingsystems now in use reveals that most of the systems are of a relatively simple nature, comprising only a few sorts and having `very few items in the system at one time. The control for these systems is primarily mechanical and, although quite ingenious in' some cases, is limited to small systems.

As the desired sorting system becomes larger, it has been necessary to change the method of control to` one involving electrical relays. As still more size and com'- Patented Sept. 19, 1961 and the United States Post Oice system coordinated therewith. Each of the areas will be assigned a common destination, accessible to the railroad network, to which `all of its mail and parcel post packages will be directed. Railroad cars at the installation will be assigned to each of these area destinations. These railroad cars willbe directed to the above mentioned positions adjacent the conveyor sorting belt.

In each of these conveyor unloading positions, one or more persons are located to remove packages from the belt for -loading on an adjacent car which is to carry the packages to their respective area destination. Thus, in a typical sorting installation, for instance Philadelphia, several of the unloading positions may have cars for each ofseveral medium sized cities in the adjacent localities in southeastern Pennsylvania, New Jersey, Delaware and perhaps Maryland. One person at each unloading station would be responsible for removing packages destined for the respective city from the belt and yfor placing it ,on a gravity conveyor extending to the desired car. For a distant major area destination, such as Chicago (which might receive packages for rerouting to all of Illinois) another car, or cars, will be assigned a dierent position along the belt. However, in this instance, it may be necplexity was added to systems, magnetic tape has been y resorted to in a few installations. These magnetic tape installations are subject to excessive wear and breakage. They are made asY a si-mple analogue of the conveyor'.

Industries such as the railroads, which are chie'y material handlers, are now lookin'g to automation to help solve some of their major problems. The railroads handle and sort a very large quantity of mail and parcel post. These mail bags and parcels are sorted primarily by hand at the present time, and the quantities are so large and the sorts so numerous that the control problem becomes a diicult one. The prior art systems have been found to be inadequate. A type of control is needed which will b'e Vrugged and trouble free. It' must also be extremely versatile so that it is applicable to a variety of systems of Va complicated nature.

Accordingly, the present invention has been particularly adapted to solve the many ditiicult problems `facing the railroads in their mail and parcel post handling locainvention is not to be so limited and 4that it maybe adapted readily to the control of conveyor and materials handling systems generally.

In order to provide ease of description, it will .be assumed that the present invention is beinggutilized to replace or supplement an existing mail and parcel 'post sorting installation in a -major metropolitan area. This installation is owned and operated by a' major railroad serving the area. The existing 'installation utilizes a conveyor belt with one Vor more persons loadingthe belt with packages `at one end. A plurality of persons manually remove the packages at selected spaced positionsalong the belt. Each of these positions identities `an area adjacent a spur track having a freight car which is to be utilized to transport packages to a predetermined destination.

With respect to this one installation, the United States and all foreign countries of the world must be divided into areas determined by the available railroad facilities tions; however, it is to be understood that the present j code. The address code for each package (or mail sack) will be placed into an electronic control apparatus by an operator subsequent to its placement on the belt; and, when the package reaches a belt position at which it is to be removed, a transfer mechanism will automatically remove the package from the belt and place it upon the desired gravity conveyor.

It will be appreciated that extreme flexibility in the control apparatus is necessary to permit complete flexibility in the iassociated railroad track system. It is necessary that -railroad cars destined to any one of the .many geographic areas be permitted routing toany one of the number of tracks terminating at the unloading positions `adjacent the conveyor belt. Due to the complexity of railroad connections and schedules from day to day,

and for that matter on any given day, it is not feasible to always route cars destined for one geographic area to the same location adjacent the conveyor belt. Inorder to permit such ilexibility, the present invention provides a means whereby a fixed address code assigned to a particular geographic area may be translated into a second code corresponding to a transfer mechanism at any one of the unloading positions adjacent the belt. Translation of a geographic area code from one transfer mechanism code to another is accomplished by the simple expedient of a modular type translator with plug-in code manually on the belt with their addresses facing upwardly., 'Ihe addresses are read by operators adjacent tlie loading area and recorded in the control apparatus.

'Ilhe address codes are advanced to succeeding positions in the control apparatus coincident with the movement of the respective packages along the conveyor path. When the packages reach the respect-ive positions at which they are to be removed, address code detecting equipment senses the presence of the respective address codes Yof the belt as it stretches over a period o f use. Vpreferred embodiment includes a bank of lights positioned -alongthe edgeofthe conveyor beltk in theareain which and initiates the operation of the desired transfer mechanisrns to selectively remove the :packages from the belt. To overcomethe numerousinadequacies vof the p rior art systems, the present invention utilizes a unique o verall Varrangement of electronic control apparatus which insures extreme flexibility, simplicity of maintenance, and unusually reliable operation. At the same time, the present invention makes use 'of a unique and trouble free, high capacity information system for routing objects to any one of a number' of transfer positions along a conveyor belt. 'I'he system is characterized by astationary, trouble yfree vanalogue 'of the moving belt.I YInstead of Yrequiring moving parts as have prior art systems, the present analogue utilizes `stationary multigdigit information storage stages andthe 'transferfof information from 'stageto stage by means of electric pulses. y.

By utilizing lthe'electronic circuitry disclosed herein, the speed of which is phenomenally'faster than the "move ment of the objects on the conveyor belt, timing problems in the control apparatus are reduced'toa minimum. The only remaining limitations from a time standpoint are dictated primarily by 'the speed at which transfer i mechanisms can remove packages from the belt and'be prepared 'for subsequent operation to remove a next -suc- 'ceeding package. Another limitation 4is the 'speed atwhi'ch packages maybe loaded upon 'the belt either manually 0r automatically and the speed at which the routing in- Vformation foreach package may be entered'manually or automatically into the electronic control apparatus. Improved transistorized circuitry has been utilized to provide a unique yet simple and trouble 'free operation as well as to provide a rugged and compact installation.

Accordingly, it is a primary object ofthe present in venti'on to provide an 'improved electronic package sortation system which permits extremeexibility 'and freliability. Atle'ast 'a portion of thefflexibility is assured by the adaptability of electronic, transistorized equipment to modular construction. Inthe present system, Vthe transistorized circuitry may be entirely 'modular with plug-in circuit boards which are easily checked `for jfaults and easily replaced by similarly constructed modules By means of plug-in modular construction techniques'for K applying routing information to the control circuitry, ixed unchangeable keyboard codes may be assigned for known destinations, even though the conveyor path transfer point may from time to time vary for such destination.

It `is another primary object of the present invention to provide a main routing V information storage device synchronized with conveyor movement, a non-synchronous routing information storage device, andujnique circuits correlating the functioning of both storage devices thereby 'to permit a (faster, more exibi'e, and 'more 'e'i- .cient system.

-It is another object of the present invention to provide a unique means Yfor marking the conveyor belt positions with respect to which objects are to be centered, which means automatically compensates for changes in the length The packages are loaded manually on the belt and inwhich operators enter the routing information of the packages into the control apparatus. ,Succeeding lights along the conveyor belt path aresequentially lighted to indicate the which packages are to be handled by each operator.

It is another object of the presentinvention to ,pro-2 `vide improved timing means for the control circuits.

It is another object of the present invention to provide a conveyor and its control apparatus which permits the 4 Y removal of packages from either side of the conveyor by a single transfer mechanism.

Other objects and the numerous features of the present invention will be appreciated upon a perusal of the followingdescription taken together with the accompanying drawings in which, c

FIG. 1 is a diagrammatical representation of a conveyor and its control apparatus;

FIG. 2 shows akeyboardcircui-t Vand a code distribution plug circuit;

' FIGS. 3 and 4 show'representative circuits of a :buffer memory unit for temporarily lstoring routing information;

FIG. 5 shows representative circuits `of a main memory unit for storing routing information;

FIG. 6 shows typical circuits for a decoder and motor control circuit for Vselectively rcontrolling the operation of a respective transfer mechanism;

FIGS. 7 and 8 show the timing .and pulse forming and shaping circuits, and FIG. 9 is a diagram of assistance to show the arrangemen-t of FIGS. 2-8. l

The preferred embodiment, disclosed in FIGS. 1-9 inclusive,`comprises a conveyor 1 (FIG. 1) and control apparatus 2. The conveyor 1-includes an endless 'belt 3 carried by a pair of spaced rotatable assemblies vv4 and 5. One of the -assemblies 4 or 5 is connected to a prime mover (not shown) which rotates the assembly to 'cause the upper port-ion of the belt to be moved along the path 6 yfrom left to right with respect to 1"`IG.-1. The conveyor path 6, as it progresses from left to right, is divided into a `plurality 'ofareas in which different `functions are performed. Thus, packages 7 are placed on the belt 3 at a loading area 8, move past apair of marking areas 9 and l10, and thenceY through a discharge area comprising a plural-ity of discharge "stations 11-`1 to 11-39. f z

lThe loading area Sand the marking areas 9` and 10 include banks of lamps 12H1 to 12v-12 inclusive. Each bank of lamps, 12-1 to 12-4 includes a plurality of lamps 13 which are energized sequentially in synchro- 'nism with the movement of the belt 3 to indicate a vbelt position with respect to which a package is Vto be centered by an yoperator in the Iloading area '8. The 'lamps inthe marking areas 9 and 10 are energized sequentially in such la fashion Ias to indicateto operators in the VVmarking areas which packages are intended for individual handling vby them.

Keyboards 200-1 and '200-2 are provided respectively v"for the operators in the marking areas 9 Iand 10. These keyboards are utilized by the operator-s to insert or Write into vthe control apparatus 2 coded information corresponding to the destination of the packages 7. The keyboards are preferably :movable lalong lthe conveyor path kso that the' operators have more freedom of movement to follow packages with addresses which areditficult to `be1t 3 which are approaching the discharge station.

vThe discharge station 11`1 includes a transfer ymech- 'anisrn V16-1. The mechanism 16-1'imay be operated in Veither- :directionto discharge packages from the belt 3 to gravity conveyors 17-11A and 17-1B` disposed on -"opposite lsides of the belt. Each of the lother discharge stations include similar transfer devices and gravity con- `veyorsfon one or bothsides of the belt 3l. Hence, station 11'39 includes a transfer mechanism 16-39' land gravity conveyors 1,'7-39A and 17-39B. An additional chute 18 is provided iat Ythe end of the conveyor to receive pack- -ages which were not removed -at any -of Athe discharge stationsY For example, a defective decoder may fa'il to operate its associated transfer mechanism.

As indicated above, the keyboards 20d-1 and 20u-2 fue Each distribution plug unit..sucl 1 as 201-1 includes a distribution board, to bedescribed later, for each decimal address code formed by the keyboard 120.0-1.V These boards are of a plug-in typeso that, the .binary .code

corresponding to a decimal code may 'be easily changed. v t

"Buffer memory units 300.- ;1and 300-2 are connected respectively to the outputs lof the distribution plug units 201-1 and 201-2. The buffer memory units arentilized for temporarily storingthe-binary address codes of -alternate packages 7 until the packages arrive yat a position o n.

adjacent the first :discharge station, 11 -1. The packages are then detected bythe photosensitive device 15a-nd their corresponding'address codes are, transferredfrorn therespective buifer memory unitsinto'a main memory unit 500.

The main memory 500 comprises a vmulti-stage'shift `register stage which rcorresponds to a transfer station.

The decoders examine the addressr codes shifted into their -associated shift register stages and cause a transfer mechanism to be operated in the event that the address codel indicates that the package is to tbe removed at the discharge station corresponding to the decoder and main memory stage.

Thetiming for thevarious operations of the control apparatus 2 is .provided by means of a clock pulse generator 700, a clock pulse amplifier 701, and a m-aster timing switch 702. Control pulses yfor certain of the main memory operations are amplified and properly shaped by a zone'pulse amplifier 800 and a reset pulse amplier 819. `l

.. Keyboard 200--1V The keyboard 200-1 (FIG. 2) is similar to commerciall'yavailable devices and will be described only briefly. The keyboard 20041 includes two rows of manually operable keys 210 and 21|1 for selecting respectively the tens and units digits of a decimal code.. In the preferred embodiment, the row 210 is1provided with keys 0 4 inclusive and the units row is provided with keys 0-9 inclusive. ,Accordingly it will be appreciated that the numerals 00 to 49 inclusive are available. When any one ofthe tens keys is depressed by an operator,- a pair of contactsV (not shown) will be closed to connect a common 4incoming .wire to V`a seletced outgoing Wire.

Thus, whenfk the tens key 4 is depressed, the incoming wire 212 is vconnected to the outgoing wire'213-4.

'l `|When anyone of the units keys Iof the row 21.1 is

depressed, it actuates fivecontacts (no-t Shown) to. engagedive conductor busses (not shown). Each .buss is connected t-o oneof thefive incoming wires 213-0 to 213-4 from the tens 1rowof keys 210. Each of the five .contacts is connected to an individualV outgoing conductor. Thus, if subsequent to the depression of the tens s wsiinilarly, ythe conductor 212 rnay be connected tov any one of the 50 conductors 214-00 to *214-49 by way of therensaewf keys 21 assises @wratten .2.11-

,halseys .in @Choi-s was er. mechanics'llynteri .lookedIk .to prevent a simultaneous depression of more thanone4 key. Each-ofthe wires/214700 to 214-49 vare connected. to ag respective distribution board'- in l.aAv distribution plug .unit ,201#1.' For example, the wire'214449 isllgankelcfedtas disribunoa'board `21s by .way 0f a socket 216 and a mating 'plug 217'.` Eachdistribution board, suchas 215, includes a circuit 'for forming a siX bit, binary code.' Thusboard V215l includes apiirst group of terminals "218andagsecond groupof terminals ,219. Erom top to .bottomthe vtermi'nalsfin `each group representvv succeeding" positiolis i'n the'hinarycode. The 'third terminal-sin leach group 218 andfZl'Qf are connected with each' otl1,e',`r"byE wayof conductors'220 tand221" and a diode 2122. Thus, theboard 215 forms a binary code 001100./,A second lboard 225 kforms-the binary code 01 1.000.` Y`..['l;\`e terminals 219 ofthe board .215 vare connected to c'zomzluctor'sl 231 Vto '236 inclusive byway of plug yand socket assemblies 23:17. The 'output terminals suchfas .2f-19of leach of the distribution boards in the unit 20L-lare miiltipled`with` thelconductors 2314236.' Eachdigital 'code'numberror' address, cod'e corresponds t'o'one ofthe gravity conveyors 1and' `its transfer mecha'- indicative "of apredeterrnined shipping destination for a particular'geographical area; It will bey seen that, since th. distribution boards, such fasQZlS, ,are replaceable, witg-is `possible to. change .the `discharge stationfand/or A gravity conveyor at which packages destined for a certainy shipping destination are to be removed. This is accomplished. by merely inserting a new board with the address code corresponding to thedesired gravity conveyorLL ,y Y,

` Therefore, it can be appreciated that extreme flexibility is provided for permittingvfirailroad cars destined for a particular shipping destinationyto be brought1 alongside any onel of the gravity conveyors such-as 1FL-1A associat'ed"with the main sortingrconveyor 1.- .p

l (Returning to the keyboard 200-1, `it can be seen lthat a Vconventional enter barfswitch-240-is,provided for releasing the tens and units keys afterthey havebeen depressed and for causing the selected digital address code to be transferred to abuffer memory'un-it 300-1 (FIGS. 3 and 4). Theenter bar switch 240 also causes a next succeeding storage. device inthe buffer memory to be connectedto the distribution unit '201-1 afterthe. selected address code has been transferred thereto. This 4Will be described inmore detail later. yThe release of the tens and units keys is accomplished in a well lknown manner by means ofrelease coils .241. A pairgof corr- Veyor start and stop switches,242are providedat the keyboard 200,-1. i

of the neon Atubes `are connected to a positive holding'potential byway of diodes i312-1lto 312-6 and resistors 313-1 and313-2gl The upper relectrodes of the neon tubes are also connected respectively'to the first contacts S20-1- to 320-6 of the top six: levels 'of the read-in switch 301 by way of conductors 314-1 to S14-6. With this circuit, a neon tube will beiired 'ifla'positive' yoltage` greater than approximately 130 volts is applied tov its corr'esp'ondingfleadsuch as 314-1. 'Ihe holding potential of volts D.C;'wil1 maintain' the neon in the conducted state subsequent to tiring.

The above 'described conductors y231 and 236 inclusiveyin the distribution plug unit 201-1 vare connected respectively to the wipers 304-'1'to 304-6 Vof the top six levels f the read-in switch 301. The enter "bar switch 240 described aboveA connects a minus 24 volt potential to 'an operate relay 303m the buffer memory unit 300-1 by way of conductor 306 to 'complete an obvious circuit fotoperatingthetelay.

When the relay 305`ener'gizes, it closesV contacts 307 to complete'a circuit for writing a selected digital address code into the lstorage vu'nitto whichlthe wipers 304-1 to 304-6 are connected. Thus, `with the connections.

shown in FIGS. V2, 3, and 4 and with the tens key 4 and the'units keyy 9 depressed, relay 305 completes a circuit from 'ai positive 1'50 'volt DLC. potential ythrough confacts 307, conductor 212, the depressed tens key 4, conduc'tor" 213-4, the depressed units key 9, conductor i4-49, socket 216, 4plug '217, conductor 220, diode zzz,

conductor 221, socket assembly 237,conductor 233, wiper 304-3, contact 320-3, conductor 314-3, to the neon tube 310-3 to lire the tube. ySince none of the other terminals y218 or 219 in the distribution-board 215 (FIG. 2)` are ednnested,V only tlieftube 310-3" vis ignited. Thus, 'the address code '00l000'is'stored inthe unit 303-1.

Whentherelay 305 'ener'gi'zes 'las described above, it also closes contacts 308 l'to energize the stepping magnet M309y ofthe Vread-in vswitch 301. The switch 301 is a conventional non-'homing selector stepping switch which advances its wipers one 'step incident to the 'de'ener'gization of-its magnet M309. l

When the magnet M309 ener'g'i'zes, it'closes contacts 321 to complete an obvious circuit 'including conductor 322 for operating 'the above described release 'coils 241 (FIG. 2) for releasingthe depressed tens and' units keys offtle keyboard L200-1. The "interval of time between `the"initia1 e'nergization ofthe relay 305 andthe `sfub'seqient energization of the'r'elease coils 241 is more than su'ieient for writing thezselected address code into the storage unit 303- 1 before the vrelease of the units'and ten'sjkeS/s., Whenjthe magnet M309 deenergizes, 'the wipers 304-1 yto .304-7 are advanced lto the next 'ac'- cessiblecontacts. 's s v s s v It will lbe recalled that a :positive voltagefsomevvhat le`s"s than 150 volts applied to the conductors 314-1 to 314-6 vwill lire the corresponding ne'o'n tubes. Attention is directed 'again to .the distribution plug unit`201-1. The -150fvolt potential was applied by wayof'the Jdiode 222 r`to 'the conductor 233. Note that, in the distributor board 22'5, thediode 244 'is also Lconnected to the conductor. 233 and, therefore, to the positive 150 volt DC. 4potential,although its polarity 'is such that 'the diode 244 should not conduct. However, it is well known that semi-conductors of the type contemplated herein have a reverse to forward resistancekratio in the order of 100:1. Thus, there will be a current flw inthe reverse direction through the diode 244 if a circuit is completed. The vvdiode 244 is 'connected -to' a second diode 243 and thence to the conductor 234. Therefore, -a low :positive potential will also be applied to conductor 234 when -the 1'1'50Y volt source connected directly to the conductor 233 -by way of r-#diode 222. It will be appreciated that when, `as `in the present embodiment, as vmany as V50 distr'ibuton boards are connected and utilized forthe vari- Yous `reipiir'ed `address codes, that the number Aof circuits fsuch as 'the one described above, will be considerably high in number; IEachfone of these 'circuits will bein parallel with several others; and, in some instances, a voltage considerably higher than 100 Volts will apply to ltine "of the conductors '231 to 236 to cause the erroneous'iiringof a'buier memory neon tube, y Y p s vIn yorder to obviate any erroneous :tiring of the neon Vtubes in the manner described' above, a clamping circuit 330;is'provided. The'circuit -330 includes series conductors`l231 to 236 and a 100 volts. The diodes 332-1 -to 332-6 gare connected such that positive volts `applied to anyA one Eof thecon ducto'r's 231 to 2316by way of the above described feedback circuits will be reduced to the positive I100 volt supply. However, they will not prevent the firingsof Ia neon tube when the positive 150 volt Vsupply 'is connected directly to the conductors 231-236. yIn ordertomain'l tain the potential connected to the diodes 332-1 to 332-6 constant, a voltage regulator circuit '333 is providedj The circuit 333 includes a gaseous discharge tube v3321- which will pass more or less current to maintain the vjunction 335 at plus 100I volts- The operation of the read-out selector switch 302 will now be described. In the event Ithat there are no packages between the marking zone 9 and the iirst't'r'ansfer station 11-1 with address codes inserted intothe'f'control system 2, then the wipers 340-1 to 340-7 of the switch 302 will KIbe lagging the wipers 304-1 to 3'04-7 "of the nected resistancesand'diodes33;1-1Ato 331-6and 332-11 f.

to 332-6 interposed between respective ones of the conswitch 301 `by one position. 'In the event that there are such .packages between the marking station 9 and Athe discharge station 1111-1, then the wipers 340-11 to 340'-7 will ylag vthe wipers 304-1 to 304-7 by a number `of posi*- tions corresponding to one greater vthan the'number of packages. Y

The wipers 340-1 to 340-7 have access to leachof the storage devices 301-1 to 303-n by vway of succeeding contacts engageable by the wipers. The wipers 340-2 to v340-7 are connectable with the lower electrodes'ofth'e i tubes -310-1 yto 310-6 respectively. The conducting `or nonconducting state of the tubes willcause selected Voltages (tplus V15 volts or ground potential) to be 'applied to the Wipers 340-2 to 340-7 'by Way of conductors 341-2 to 341-7 and the rst position contacts 342-2 to 342-7. In this fashion, address codes can be read out of the storage units such as 303-1.

The wiper 340-41 has access to the upper Aelectrodes yof each of the neon tubes l310-1 to 310-6 by Way of its first vposition contact 342-1, conductor 341-1, landdio'des 312-1 to 312-6 respectively. The function of 4the wiper 340-1 and its accessible contact bank yis to extinguish `conducting neon tubes in each of the storage units 303-1 to 303-n subsequent to the removal 'therefrom of address codes. This will `be Adescribed in more detail later.

Wiper 340-'8 and its associated contact bank `and wiper 304-7 and its associated contact bank are wired in 'such a fashion as to light a synchronous indicator lamp 250 (FlG. 2) at the keyboard 200-1 under certain conditions. The lamp 250 indicates whether or not the read- Nin selector switch 3011 and the read-out selector switch 302 are properly synchronized with respect to eachother for properly reading address codes out of the storage units 303-1 to 303-'n at the instant the packages corresponding to the respective codes, enter the first discharge 4station area l11-1.

In order to accomplish this, the contaots'in the batik and the lamp 250 will be lit to indicate the synchronizedV condition of the switches 301 and 302.

Main memory unit 500 The main memory unit 500 comprises a transistoriied shift -register having a plurality of stagesy 501-1 to 50 1-'n.

Each stage, such as 501-1 requires six sections in order to handle the six digit binary numbers of the address codes. Each section is utilized ffor receiving, "storing,y `a`n`d transferring 'one 'bit of information succeeding "address positive supply potential *of Y audacia Codes. Hence, each stage, suchas 501-1, will receive, store, and advance the six bits of infor-mation in each address code. Each section of each of the stages 501-2 to 501-n will be identical in their makeup. However, inasmuch as the first stage 501-1 receives information from a diifering type of storage device (the neon tubes of the buffer memories 300-1 and 300-2), each section of the stage 501-1 must have a circuit configuration slightly ldiierent from the sections of the other stages.

FIG. 5 shows the circuits for typical sections 502-1 and 502-2 of the irst and second stages 501-1 and 501- 2. Section 502-1 of the stage 501-1 has its output connected to the input of section 502-2 of stage 501-2. One input conductor 505 of the section 502-11 is'connected to a corresponding one of the wipers 340-2l to 340-7 of the readout selector switch 302 of FIG. 4. The other.l input conductor 506 of the section 502-1 is connected to a reset pulse amplifier circuit of FIG. 8 which will be described in detail later.

The section 502-1 includes a pair of transistors 507 and 508 which are connectedto form a bistable flip-flop al way of conductor 5I17. The transistors also include apair of collectors 518 and 519 which are connected to a negative 20 volt supply by way of loadresistors 520 and 521 and conductors 522 and 523. The collectors 518 and 519 are also cross-coupled to bases 51-0 and 509 respectively by way of biasing resistors 524 and 525 respectively. The collectors 518 and 519 are also coupled to a pair of input conductors 526 and 5'27 of the section It will be appreciated that; since the section 502-1 is a bi-stable Hip-flop device, one `transistor 507 or 508 is conducting -while the other transistor nonconducting. When a transistor is conducting, a substantially zero potential appears at its collector. When aV transistor is in the nonconducting state, a substantially 15 volt negative potential appears at its collector. Any positive potential applied to the input to the base of a conducting transistor will cause the transistor to cut olf and cause the other nonconducting transistor to conduct.

The circuits have been varbitrarily arranged for conduction -by the lower transistor 508 and nonconduction byL the upper transistor 507 when the section 502-1 is storing a 0. Transistor `508 will be nonconducting and the transistor 507 conducting when a l is being stored by the section 502-1. Also, the section 502-1 isconsidered in its normal reset position when marked with a 0. The section 502-11 will be marked with a 1 only when a bit of a binary address code Vso'marks the section.;

It is assumed that the section.y 502-1 receives the rst position digit of each `address code. 4 The information inputvconductor 505 is therefore connected to the lower` electrode of the neon tube 310-1 (FIG. 4) by way of wiper 340-2, contact I342-2, and conductor 341-2. The potential at the lower electrode relative to `ground is applied to said conductor l505.

In the event that the neon tube 310-1 is nonconduct-` conducting, to Cut Oli lAt the Sam@ @12mths tfansml' positive l0 volt supply potential.

10 507 will be caused to conduct. Hence, the section i-1 will be storing a 1. i The erasure of this 1 from the section 502-1 subsequent to the transfer of the l to the next section 5027-2 will be described in greater detail later. However, briey; the l is erased by applying a negative 15 volt potential to the reset pulse input conductor 506. The conducting andnonconducting statesof the transistors are not aifected until the trailing edge of the reset pulse arrives. The differentiating circuit comprising capacitor 511 and resistance 512 will cause a sharp highly peaked positive pulse at the trailing edgel of the negative reset pulse, which positive pulse will cause the transistor 507 to cut olf. At the same time thejtransistor 508 will be caused to conduct. It will be recalled that the collectors 518 and 519 of the transistors 507, 508 are connected to the input conductors 526 and 527 ofthe section 502-2 of shift register stage 501-2. Hence, whenever a O is stored in the section 502-1, a negative l5 volt potential is felt at conductor 526 and a 0'potential is felt at conductor 527. Alternatively, when a l is stored in the section 502-1, a 0 potential is felt at the conductor 526 and a negative 15 volt potential is felt at the conductor 527.

The section 502-2 includes a pair of transistors 530 and 531 which are connected in a manner similar to that in which transistors 507 and 508 are connected to form a bistable flip-flop circuit. Hence, a pair of emitters 532 and 533 are grounded. Collectors 534 and 535 are connected to the inputs 536 and 537 tothe next stage and are connected to the negative 20 volt potential by way of load resistors 538 and 539 and conductors 522 and 523. Bases 540 and 541 are cross coupled to the collectors 535 and 534 respectively by way of biasing resistors 542 and 543 respectively. v

A pair of base biasing resistors 544 and 545 are connected between their respective transistor bases and a A pair of current limiting resistors 546 and 547 are provided for the transistor bases. I

',I'he input conductors 526 and 527 are connected to 'the current limiting resistors 546 and 547 respectively by way of AND circuits 550 and 551. 'I'he AND `circuit 550 comprises the conductor 526 and a series connected diode 552, a zone pulse conductor 553 and a series connected diode 554, a resistor 555, a capacitor 556, and a blocking diode 557. In the event that a negative 15 volt potential appears at input conductor 526 and also at the zone pulse conductor 553, a negative 15 Volt potential appears at the junction 558. This will cause the capacitor 556 to charge itself by way of diode 557. In the event that the negative 15 volt potential is then removed from one of the conductors 526 or 553, the capacitor 556 will discharge through the transistor 530 to cause the transistor to cutoff if it is conducting.

The AND circuit 551 is similar to the circuit 550. It includes the input conductor 527, diodes 560, 561 and 562, capacitor 563, resistance 564, and the zone pulse conductor 553. In the event that a negative 15 volt lpotential is applied to the input conductor 526 and to the When subsequently the negative 15 volt potential is removed from one of the conductors 527 or 553, the capacitor 563 is discharged into the base circuit of the transistor 531 to turn the transistor off if it is conducting.

It will be appreciated that only one of the input conductors 526 or 527 will have a negative 15 volt potential applied thereto. In the event that'a section 502-1 is storing a 0, its transistor 507 will be nonconducting and the negative 15 volt potential will appear at conductor 526. In the event that the section 502-1 is storing a 1, its transistor 508 will be nonconducting and a negative 1.5 volt potential will be applied at the input conductor 527.

As will be described in greater detail below, a negative 15 volt potential will be applied'to the zone pulse conductor-553 to transfer the address codes in the main memor-yj 500 .to nextsucceeding stages Aeach time that the/conveyor. belt 3;moves three feet. -Hence, each zone 'pulse willadvance lthe code bit in section 502-1 to section 502-2. l i

If the section 502-2 .has the code bit 0 transferred thereto, its transistors 530 and 531 will assume nonconducting conducting states respectively. A negative volt potential will appear `atthe .input conductor 536 to the nent' succeeding stage. Thisnegative 15 volt potentialjwill also be applied to theconductor 566-. Also, since the transistor 531 is conducting, la 0 potential will ybe applied .tothe conductors 5317l and 567.

. Alternatively, in the event that aA 51 is `shi-fted into the f vvsection 502-2, a negative 15 voltpotential will be applied totheconductor 567 and a 0, potential to the conductor .566. ,One of the conductors 526 or 567 are connected toeach of the corresponding inputs to the decoding cir- .c'uits i600-IA and 600-1B 'associated therewith. In the revent that the address code to be detected by the decoder 60G-1A includes a l in the digit `positionstored by the section 502-2'then the circuit n600-1A vis connected to the conductor 5,67. Alternatively, if the digit position inacludes a 0, the circuit 600-1A is connected to the cont ductor 566.

Decoder circuits 600-1A and 6'00-.IB and motor control circuit 6'01 FIG. ,6. shows the decoder circuits y600-1Aand 600-1B and the vmotor control circuit 601, all of which are associated with the transfer mechanism 16-1 (FIG. l). VIIt `willbe assumed Afor ease Vo-f description that the distribution boards 215 and 225 of FIG. 2 respectively deter- .mine the address codes to be detected by the circuits 60,0-1A and 600-'1B respectively. Hence, circuit 600-1A `will detectthe address code 001.000 and the circuit 600- 1B will detect 001100. Y

Accordingly, the conductors 602-1 to 602-6 and their l `series connected diodes 60S-1 to 60-3-6 are connected` to -the Acorresponding sections of the shift register stage V501-2. in such la fashion as to .detect the presence or absence'of the desired digits. As described above with re- ,spect `,tothe main memory section 502-2, the conductor 566 isfconnected to the circuits 600-1A and 600-1B in the event that the corresponding digit is a 0. Assume that the section 502-2 stores the first position digit and that the-conductor -602-1 vdetects the iirst position digit. Since the address code for the lcircuit 600-1A `is 001000, the `conductor 602-1 will be connected to the conductor '.566 vof the main memory section 502-2. Similarly the conductors602-2, 602-4, 602-5, and602-6 will be con- 'nected -to conductors corresponding to 566 in the second, fourth, fth and sixth sections of the mai-n memory stage 501-2.` The; conductor 602-3fwill be connected to av conductor corresponding to 567 in the third section of stage .501-2.

l The conductor 602-7 of the decoder 600-1A is connected to a predetermined contact in the master timing switch 702. As will vbe described in greater detail later, the master timing switch 702 applies a negative potential to the .conductor 602-7Hat eachinstant in time When a conveyoribelt position, withrespect to which vpackages are centered reaches the center of the discharge mechanism 16-1 (FIG. 1). The purpose of this arrangement ,is .to Yinitiate the operation of the trans-fer mechanism only after the package center and the mechanism center are aligned, thereby to accurately synchronize the opera- -tion of the transfer mechanism with the movement of packages it is to remove from the conveyor belt 3.

Thus itcan be seen that the decoder 600-1A is a seven- .i-nput AND circuit in which six inputs determine the rpresence or absence of the assigned address code and the seventh inpu'tsynchronizes the operation of the associated transfer mechanism with the moving packages. negative potential appears at all seven inputs -to the *de- When ay fout selector switches.

coder 600-1A, a neg' tive .potential appears at 'thejunction '5. This negative potential will cause .a 'transistor Y606 toconduct, thereby to operate a relayY 607. The relay 607 "closes contacts608 which energize amotor start solenoid 609 ofthe motor control circuit 601.. .The solenoid 609KV will operate contacts (not shown) Vto operate a reversible three-phase `motor, to rotate the transfer mechanism .16-1 (FIG. Al) toward the gravity conveyor 17-1A. Thesolenoid 609' also closes contacts A610 which hold the solenoid 609 operated when the contacts 608 subsequently open. The contacts 608 are closed only momentarily inasmuch as the pulse applied to the conjfductor 602-7 is o-ffshort time duration as 'will be described later. lConsequently, the'AND circuit will cause f only momentary operation of the transistor 606' and the relay 607. 1

`Alfter the transfer`mechanism 16-1 has mad'eon cycle of operation to discharge a'package, a limit switch 611 is operated by the transfer mechanism '16-1 to open contacts 612. The solenoid 609 restores to deenergize the motor. lThe motor circuit `601 `also includes a second solenoid 613 which operates contacts (not shown) to energize the motor of the transfer mechanism 16-1 in a direction vopposite that controlled by the solenoid 609. The solenoid 613 -is controlledV by the decoder circuit 600-1B inV a manner similar to the control of the solenoid 609 by the decoder 600-,1A. The solenoids 609 andv 613 are mechanically interlocked to prevent the op- `erationof one while theV other is energized.

The decoder circuit 60G-1B is similar to decoder 600- 1A. Therefore, it has six information input conductors 620-1 to 620-6 and one synchronizing input conductor 620-7. The decoder 600-1B also includes diodes v621-1 to 621-7 which'act as'` inputs of an AND circuit. It has been assumed that Ythe address code 00ll00'of the distribution card 225 is the code which is assigned to the decoder 600-1B of the discharge station 11. Hence, when said assigned code is stored in the main memory stage 501-2 andwhen subsequently a synchronizing pulse is applied to the conductor 620-7, a negative potential will beapplied to the junction 622 to cause a transistor 623 to conduct. relay 624 is energized upon conduction 4by `the transistor 623. Relay 624 operates contacts 625 to complete an obvious circuit for operating the motor start solenoid 613. The solenoid 613 causes the conveyor transfer mechanism 16-1 (FIG. 1) to operate in a direction opposite to that in which it was operated by the solenoid 609. When the mechanism 16-1 completes a cycle to discharge a package on the gravity conveyor 17-1B, the limit switch 611 will open contacts 612 to restore the solenoid 613 and stop the transfer mechanism motor.

T irnt'ng and synchronizing circuits The timing and synchronizing of the various operations of the present system are `shown in FIGS. 7 and 8. FIG. 7 discloses an electromagnetic clock pulse generator 700,

ya clock pulse amplifier circuit 701, a master timing stepping switch 702 operated by the generator and amplifier, the photosensitivedevice 15 .for detecting packages l7 on thefbelt-S, `and `a package stretching and lcounting circuit 79,5. v

gThe"'photosensitive device V15 (FIG..7) may be any |`one of a number of commercially available devices including appropriate amplifiers. Each time that a packl) fand the photosensitive device `15, an amplified output pulse will be applied to the conductors 740 and 741 (FIG. 7). This pulse will energize a relay 742. The pulse may have positive and Vnegative half cycles; and, therefore, a diode 743 is connected across the relay 742 to short circuit one of the half cycles. When the relay 742 is operated, it closes contacts 746 to prepare a circuit .for .energizing the magnets, such as M350 of the read- A-capacitor 744 is also connected across the relay 742 to store venergy for maintaining the 13 relay energized for a longer period of time. This provision is desirable in the event that some ofthe packages 7` are very short.

The photosensitive device must detect a package at the same time that the master timing switch 702 reaches a predetermined position in order to advance the readout selector switches of the butfer'memory units 300-1 and 300-2 to their next succeeding positions.' Unless the capacitor 744 is provided, it is possible that the photo.-` sensitive device 15 might sense a short inaccurately` positioned package to cause the relay 742 to` energize and deenergize before the switch 702 reached its predetermined position. In such an event, the respectivebuier kmemory readout switch will not be advanced and synchronization between succeeding packages rand their respective adA dress codes will be lost. To avoid this situation, theV capacitor 744 is made suificiently large to maintain ther relay 742 energized for a suflicent period of time to assure the operation of the readout switches.

Asolenoid 745, which operates any one of the nurnber of* well known counting devices, is provided to count the number of packages detected by the unit 15. i

' The electromagnetic generator 700 may be 'any one of a number well known in the art for producing an output pulse in its coil 710` for each revolution of its magnetic structure 711. The'structure 711 in mechanically connected in any well known manner to the means for moving the belt 3 of the conveyor 1. 'Ihe structure 711 completes thirteen revolutions during movement of the belt 3 a predetermined distance, for example three feet. It willl be recalled that the minimum distance be,- tween packages in any system will be dependent upon the minimum time which a transfer mechanism, such as 16-1 (FIG. 1) requires to remove a package and be prepared to remove a next succeeding package. The function of the clock pulse generator 700 is tto provide precise timing for the various control apparatus functions. Thus, the timing between the package movement and the control circuits can be held to within at least 36/ 13 inches. It will be apparent that the timing can be made even more precise if desiredgfbut this has not been necessary in actual installations with existing belt speeds.

three foot distance is also utilized to divide the conveyor path into a plurality of fixed Zones for assuring the' `operation of the transfer mechanisms only when packages are properly alignedtherewith. We will see in detail'later that each lamp bank 12-1 to 12-4, determines the instant in time at which a package centering position of the belt passes the forward edge of the respective bank. This forward edge is arbitrarily made the forward edge of a zone. Each bank is three feet long and, therefore, defines a zone. Succeeding three foot zones are marked off accordingly.

It will also be seen that the each bank 12-1 to 12-4 is in turn controlled by the master timingv switch 702. Therefore, the entry of a package centering position on the belt into and through a Zone has a denite relation-y ship with the movement of the switch wipersto succeeding positions. l

VThe position of the center of each transfer mechanism relative to the forward edge of the zone in which it is located must bedetermined so that its respective decoder can `be synchronized to actuate the mechanism when `a package center coincides'with the transfer mechanism center. Then the position, in which the :switch wipers are located when each package centering position ofthe belt reaches this transfer mechanism zone position, is utilized for timing the operation of the respective decoder.

The output of the electromagnetic generator 7001 is fedto the clock pulse amplifying and shaping circuit 70-1. The voltage produced by the generator will have both a positive and anegative half cycle.` `The diode 712 shunts the positive half cycle of they induced voltage allowing only the negative half cycle to remain. This negative a monostable, multivibrator'which produces one output.

pul'seffor each negative input pulse. The negative pulser on the base of the transistor 713 causes the circuit to` ip,rthat is, it causes the; transistor 713 to start conducting and transistor716 to cease conducting. The circuit. remains inl this condition for a duration of time de pending upon` the values, of the coupling capacitor 717 and theA base connected resistances 7118 and 719. The output pulse taken from the` collector 720 of the transistor 716 is a negative pulse which is applied to the base of` a transistor 721. As4 is well known, this negative output is produced by virtue of the fact that the collector of the transistor, when nonconducting, is somewhat below the negative potential (minus 20 volts) to which it is connected; whereas the collector voltage is substantially at ground potential while the. transistor conducts.

. The negative output pulse from the ytransistor 71,6 is inverted to avpositivek pulse by the transistor 72,1. A succeeding-transistor 722 reinverts the pulse back to a negative pulse. This negative pulse is. applied to a power transistor 723 which momentarily energizes the magnet M724 of the master timing switch `7011 over an obvious` circuit. f

Bach'time that the magnet M724 deenergi-zes subsequent Ato its energization by the power transistor 723, it advances the wipers 725-1 to 725-6 of the switch 702 one step to the next succeeding contacts accessible lthereto. Thus, it will be appreciated that asthe conveyor belt 3 moves a` distance of three feet, the clock pulse generator 700 will produce 13 output pulses to cause the magnet' M724 to advance the wipers 725.-1 to 725-6 thirteen steps. t Certain of the control functions or the control apparatus 2 are performed once for each rthree foot moveb ment of the belt. Certain other timing functions of the control apparatus 2 are performed only once for each six foot movementof the belt. 3. Accordingly, each contact bank accessible to the wipers 725-1 to 725-6v is provided with 26 contact positions. When a contact bank is utilized to control la function which occurs once with-'each threel foot movement of the belt 3, the corresponding contacts in the rst and4 last half of the bank are multiplied. l l

The first level 730 of the switch 702 is utilized to control three functions of the control apparatus 2. l yThe first and `fourteenth contacts 731 Iand 732 are multipled and are utilized for resetting thegneo'n tubes in thev buier memory units 300-1 and 300-2. The thirteenthand twenty-sixth conta-cts 737 and 754 are utilized to initiate afzone Vpulse for advancing address codes in the ,main memoryl 500. The seventh and twentieth contacts 736 and 760 areutilized'to initiate a pulsel for resetting the input stage 501-1 of the main memory. i

The resetting of the neon tubes 310-1 to 310-6 will nowbe described. When the wiper 725-1 is in engagement with contact 731 or 732 a circuit is prepared for energizing the'erase relay 840 (FIG. 8'). The next: en-v ergization of the magnet M724v (FIG. 7) closes contacts 755 tov energize the relay 840 over the circuit extending- Vfrom a negative source of potential, through contacts 7515,

conductor 756, wiper 725-1, contact 736 or 760, conductor 842, and the relay 840 (FIG. 8) to. ground.

The relay 840 closes contacts 841 to extend ground potential to the upper electrodes of the neon tubes 310-1 to 310-6 by way of resistance 843, contacts 841, conductor 844, wiper 340-1 (FIG. 3), contact 342-1 (assuming that the wiper has been advanced previously to contact 342-1 to transfer its address code to the main memory unit 500), conductor 341-1, and diodes 312-1tnok- The negative pulse causes the. transistork The zone pulse amplifier 800 A(FIGS. l and 8) will now be described in detail. One zone pulse is `generated for each thirteenth (13) output `pulses of the clock 'pulse generator 700 and, therefore, for each 3foot movement of'thebelt 3. Thus, each time that themagnet M724 ('FIG. 7) is energized by a pulse from the generator 700 andamplifier 701, whilethe wiper 725-1 is in engagement with either contact 737 or 754, a circuit will be completed for generating a zone pulse. This circuit extends from a negative 24 volt supply potential through contacts755 which are closed upon energization of the magnet M724, conductor 756, wiper 725-1, contact 737 or 754, contacts 796, and conductor 757 to the zone pulse amplifier 800 (iFIG. 8). The contacts 796 close only momentarily incident to the energization of the magnet M724.V v

The zone pulse amplifier 800 includes an input load resistor 806 across which the above mentioned negative 24 volt potential in applied by way of the master timing switch 702. `The zone pulse amplifier 800 also includes a pair of transistors 807 and 808 with associated circuit connections providing a one-shot multivibrator similar to the multivibrator described above in the clock pulse ampliier 701. The lcircuit is arranged such that thetransistor 808 is normally conducting and the transistor 807 normally` nonconducting.

The negative pulse applied to the input resistor 806 causes the transistor 807 to conduct and the transistor 808 to cease conducting. After a predetermined time interval, the transistor 808 will again conduct and the transistor 807 cease to conduct. During the time interval that transistor 808 is nonconducting, 'a negative potential appears at its collector 809. This negative potential is applied to a transistor circuit 810 which inverts the pulse to cause a positive pulse to be applied to the collector 811. T'he positive pulse appearing at the collector 811 is lapplied to the base 812 of a normally conducting power transistor 813 by way of a current limiting resistor 814. Hence, the power transistor 813 will cease to conduct for a short time interval determined by the length of the pulse applied thereto, thereby to produce a shaped and amplified negative output pulse at its collector 815. p

The collector 8 15 is connected by way of a conductor 816 to the input conductors such as 553 (FIG. 5) to the AND circuits, such as 550 and 551 (FIGcS), in all sections of all of the main memory stages 501-2 to 501-n inclusive. ltwill be recalled that this zone pulse causes 'thetransferof address codes from stageto stage in the main memory 500 in synchronism with the movement of the packages 7, to which the address codes have been respectively assigned, into discharge stations, such as11-1, corresponding to the respective main memory stages.

. The reset pulse amplifier 819 is shown diagrammaticallyuin ljllGS. l and 8. The amplifier 819 may be'identical to Athey input and one shot multivibrator portions of the zone' pulse amplifier 800; and, therefore, need not be described in detail. Briefly, it will produce a shaped'and amplified negative output pulse at the conductor'817 inf cident to receiving a negative input pulse at conductor 8 1'8.` However, since the inverter and power'. transistor of the zone pulse amplifier are not included in the reset pulse amplifier, the output pulse will have less power.

`The Vcircuit for producing the input negative pulse at the conductor 818 (shown in FIG. 7) is similar to that producing the input pulse for the zone pulse amplifier 800. This. circuit is completed Vby energization of the magnet .M724 when the .wiper 725-1 is in engagement withV conatct, 736 or contact 760. This circuit extends from the negative 24 volt potential through the contacts 75,5, conductor 756, wiper 725-1,contact 736 or 760 and lcontacts 797t o conductor 818.v The contacts797 are momentarily Yclosed by the energization'of ythe magnet 724. A

f The 'negative output pulse produced at conductor 817i (FIG. 8) by the reset pulse amplifier 819 is applied 'to' the reset pulse input conductor, such as 506 ('FIG. 5), of each section, such as 502-1, of the frst main memory stage 501-1. As described above, the function ofthe reset pulse is to reset each secton, such as 502-1', tofacondition in which itis marked with a O subsequentto its being marked with a 1, which l has been trans-y ferred to the succeeding main memory stage 501-2.-

The circuits for advancing the read-out selector switches, such as 302, of the buffer memory units will now be described. It will ber recalled that the photosensitive` device 15 (FIG. 7) operates relay 740 each time it senses a package. Thev relay in turn closes contacts 746 Vto* prepare a circuit for energizing` the magnet, such as M350 (FIG. 4) of one of the read-out switches. When the wiper 725-2 subsequently engages its second or fifteenth position contacts 735 or 738, with the contacts 746 still closed, the' circuit is further prepared.

With the wiper 725-2 so positioned and with the contacts 746 so closed, the subsequent energizationof the magnet, M724 by the next clock pulse will complete a circuit for operating a respective one ofthe readout selector switch magnets. Thus, a circuit will be completed from a positive 24 volt potential, thorugh closed contacts 747 of the magnet M724, conductor 748, contacts 746, conductor 749, normally closed contacts 750, wiper 725-2, contact 735 or 738, conductor 751 or752, nor-1 mally closed contacts 801 or 802 (FlG. 8), and conductor 803 or-804, to the magnet M350 or to its corresponding magnet in the buffer memory unit 300-2. The readout selector switch of the energized magnet advances its wipers one step when the magnet deenergizes subsequentV to the deenergization of magnet M724 at the end of the clock pulse. Also, when the magnet M724 deenergizes, the wipers 725-1 to 725-6 advance one step.

When the wipers of a buffer memory unit are advanced as described above, they connect the next storage section to the main memory input stage 501-1. This next storage section has marked therein the address Code of the package just detected by the photosensltive device 15.

Provision has been made to permit the operation of the system with only keyboard 200-1 and buier memory unit 300-1 in use. In such an event, the readoutselector switch 302 (FIG. 4) must be advanced one step each time a package passes the photosensitive device 15 rather than upon the passage of alternate packages. To permit this operation, a manually operable switch 260` (FIG. 2)Y is provided at the keyboard 2001. Actuation of the switch 260 extends a negative 24 volt potential through contacts 261 Iand conductor 262 to operate a relay 765Y (Fig. 7). The relay 765 opens contacts 750 and closes contacts 766 to connect the conductor 749 to the wiper 725-3 instead of to wiper 725-2. The second and iifteenth contacts 767 and 768 are both connected to the conductor 751 which, as described above, is connected to the readout selector magnet M350 (FIG. 4). Hence, the magnet M350 will be operated each` time that the photosensitive device 15 detects a passing package 7 while the wiper 725-3 engages contact 767 or 768.v

It will be recalled that at all times one storage section such as 303-1 of each buffer memory unit 300-1 andl 300-2 is connected by way of its respective read-out selector switch to the main memory input stage 501-1. f `The two sections are therefore connected in parallel. It will be appreciated that, during normal operation ofthe present conveyor system, packages will be placed at every three feet on the belt 3 and that both buffer memory units will be partially filled with a plurality ofv address codes. i

v Provision must therefore be made to assure the transfer of correct address codes at proper intervals from themain memory stage `501--1 to stage 501-2. This is Vaccomplished by the unique timing sequence of the various functions controlled -by the switch 702. An analysis of the 17 two upper Alet/,els of .the-switch 702 with respect .to the main '-.iremcry reset. znerulse transfer, buffer .memclry reset, and biitfe'rl memory advan functions will .now 1be made to clarify ,this sequence.

It has been seen-that .themagnet M350 vis operated to advance its v'associated Wipers only once for each complete twent-y-six step cycle of Vthe switch `702. That is, the magnet M350 is operated vonly when the wiper 725- 2 engagesits second position contact 735. Therefore, each storage section tsuch as 303-1 of the buffer memory 300-1 is connected `to the main memory input stage 501-1 while the wiper 725- 2 advances from the second position contact 735 through twenty-six steps back to contact 735. Similarly `each storage section lof buffer memory unit .300-2 iS connected to the input stage 501-1 while wiper 725-2 advances from the fifteenth position contact 738 through acompletecycle vback lto Contact 738.

Assume that the system has just been put into operation and that no linformation is stored in either of the buffer memory units 300-1 or 300-2. Now assume that three packages are placed on the belt 3 and theaddress codes of the first and third package are read into the buffer memory 3 00-1 and the address code of the second package 4into buffer memory 300-2. Shortly thereafter, the photosensitive device will detect the first packlage. As soon as the wiper 725-2 reaches thesecond contact 735 andmagnetM724 energizes, the readout selector switch 302 will be operated toadvance the wipers 340-1 to 340-7 to a contactposition in which the storage .section, having the first package address code, will be connected to itheinputstage 501-1 of Ythe main memory 50,0.

A similar storage section, having no address'code, Aof the other buffer memoryunit is also connected to the input stage 501-1. Therefore, each of the six neon tubes in one storage section will have its lower electrode connected in parallel with a .corresponding neon tube in the vother storage section. When two `parelleled neon tubes `are both nonconducting bothwill extend vground Ipotential to the main memoryv stage 501-1. Whenoneof the .two parallel `neon tubes .is conducting, the positive volt- ,age` extended to the stage 5.01-1 will merely be lowered lin View of the fact `thatfthe .lowerelectrode is 4connected ,to ground by .wayoffthetwo resistances connected to the parallel tubes rather ,than .one resistance. This lowered positive .Voltage will, .hom/ever, be sufficient to l.control the input stage transistors las described above.

The .wipers 7125-110 7,25-6-are advanced yuntil the wiper 7 25--1V .engages ,the seventh position contact. A reset pulse is applied to the input stage 501-1. This is of no effect, however, lsince the storage section with the first package address code is still connected to the stage.

The wipers 725..-1-.to 725-6 continue to advance until the wiper 725-13 engages Vthe thirteenth position contact 737.v A zone pulse .transfers .the first package address code to 4the second main memory stage v50;1-`-2. The address codealso remainsjin `the input stage 501-1.

Whenthe next 4clock pulse advances the wipers, wiper 725-1 Yengages its fourteenth position contact; and the tirst package address code yis erased from the buffer memory unit 30,0-1. VWhen the next-clock pulse advarices .the wipers, .the .wiper 725-2 engages its fifteenth pos1t1on contact 738; .and the storage section-.of the buffer memory 3,00-2 `having the second package address code is connected tothe input stage 501-1.

`Since .the iirst package address code is still held by stage 501-1, each."1" of boththe first and second pack- .age address codes is marked in the stage. However, as the wipers 725-1 to 725-6 continue lto advance, lthe wiper 725-1 will soonengage the twentieth position contact 760 and a reset pulse Vwill be applied-to the stage 501-1. Each l of the first package address code will be erased from the stage, except of course the second package `address lcode included-a l in the same vdigit 18 position. Thus, only the .second package code will -remain inthe stage.

An erroneous address code in the stage 501-1 during the interval that the Wipers 725-1 to 725-6 advance from their fifteenth to their twentieth contact positions -is of no consequence. The only critical time for the existence of a correct address code is the time at which a zone pulse causes the'transfer of the code from stage 50'1-1 to the stage 501-2. This occurs when the wipers 7275-1 to 72.5-6 subsequently reach their twenty-sixth contact positions. One contact position later, storage section of the buffer memory 300-2, holding the second Vpackage address code, is reset. In the seventh contact positions of the wipers 725-1 to 725-6, the second package address code is erased from the main memorystage 501-1,

The timing of the decoders \600-1A to 600-39B will now be described. It Vwill be recalled that each of the decoders 600-1A to 600-39B inclusive periodically examines its corresponding main memory stage for the address code assigned to fthe decoder. It will also be recalled that this examination takes pla-ce upon the application of a synchronizing pulse to the synchronizing input conductor, such as 602-7 (FIG. 6), of the respective decoder.

'The decoders may be operated incident to any one of the output pulses of the clock pulse generator 700 except the pulse succeeding that which produces a zonerpnlse.

- During the time interval after the zone pulse, the main memorycircuits are stabilizing incident to the transfer of address codes to suceeding stages. The address codes cannot befexamined at -this time. The fourth level 770 4(FIG. 7) .of the-master timing switch '702 is utilized to vproduce ydecoder synchronizing pulses. It will lbe recalled that the zone pulses are produced when the wipers of .the -switch'702 are in vengagement with their thirteenth and twenty-sixth accessible contacts. Hence, any contact vin the level 770, except the lirst and fourteenth, may be utilized to initiate the loperation of the decoders. The -wiper 725-4 of the level 770 is normally connected toI a negati-ve 24 lvolt source of potential by way of conductor 772, break contact 773v of the magnet M724, and conductor 774.

VIt is assumed for purposes of description that the trans- 'fer mechanism 16-1 is positioned -With respect to the arbitrary conveyor path zones such that-the starting of ,its motor shofuld begin when the wiper 725-4 is inengagement with its second or fifteenth accessible contacts 775 or 776. Hence, the contacts 775 and 776 are-both con- `nected to the synchronizing input conductors 602-7 and `620-7 (FIG. 6) of the decoders A600-1A and-600-1B -by way of a conductor 777. "'I'herefore, whenever Vthe-mag- Vnet M724 restores to close contacts 773 and to simultaneously advance-thewiper 725-4 into engagement with contact 775 or 776, a negative synchronizing pulse will b e applied to the inputs ofthe decoders 600-'1A and 600-1B so that they may examine their corresponding main inemory stage 501-2-for the assigned address code. rIt will ,be

kappreciated Athat conductor 7.77 may also be connected to any one or more of .theother decoders in ithe control apparatus 2, in the event that their corresponding transfer mechanisms are positioned similar to mechanism 16-'1 relative to the zone in which they arelocated.

The lamp banks i12-1 to 12-12 (FIGS. 1 and'8) will `now be described in detail. As indicated above, the loading area -8 is provided with 'four banks of lamps 12-1to 12-4-each of which is three feet in length. The marking areas 9 `and 'V10 are `provided with banks of lamps 12-5 -tof12-8 and 1-2-'9 to 12-12. Each of the banks 12-1to 12-12 includes 1-3 lamps corresponding vto the 13 clock pulses produced Iwith each three foot movement of the belt 3.

In the 4loading area banks 12-1 vto 12-4, succeeding lamps in each bank will be successively energized by suc- Aage is to be centered.

, 19 in each of the banks 12-1 to 12-4 will besimultaneously energized. Hence, all first position lamps in banks 12-1 to 12-4 will be energized, then second position lamps, etc.

Lighting of the lamps in banks 12-1 to 12-4 (FIG. 8) is provided by the bank 780 (FIG. 7) of the master timing switch 702. The contacts in level 780 are accessible to the Awiper 725-5. IIt will be noted that the first thirteen contacts in the level 780 are respectively multipled with the last thirteen contacts in the level. The thirteen multipled output conductors 781-1 to 781-13 inclusive are connected respectively to lampsv 820-1 to 820-13 (FIG. 8) of bank 12-1 by way of the cable 782.

Thus, as the wiper 725-5 sequentially engages the contacts 783-'1 to 783-13, the lamps 820-1 to 820-13 will be energized in sequence. f Also, as the wiper ,7,25-5 engages contact 783-14 to 783-26, the'lamps 820-1 to 820-13 will again be energized inA sequence. Consequently, the lamps 821-1 to 821-13 are sequentially energized for each three foot movement of the conveyor .belt 3. At =any instant in time, the energized lamp in the bank 12-1 indicates the belt position at which a pack- It will be noted in FIG. 8 that corresponding lamps in banks 12-1 to i12-4 inclusive are parallel. 820-1, 821-1, 822-1 and `823-1 are connected in parallel and are energized simultaneously. Similarly, lamps Thus lamps 820-13, 821-13, 822-13 and 823-13' are connected in parallel and are energized simultaneously. Similarly, the other lamps (not shown) in banks 12-2, 12-3 and 12-4 are connected in parallel with the respective lamps 820-2 to 820-12 and are energized correspondingly. Hence, the operator at the loading area -8 will be advised of the centering positions for four packages at all times.

This means for completing the circuit for energizing the various lamps in the banks 12-1 to 12-4 is the relay 785 (FIG. 7) which is energized in response to each energization of the magnet M724. The circuit forenergizing the relay 785 extends from positive 24 volt potential, through contacts 747, conductor 786, and the relay` 785 to ground. When the relay 785 energizes, Vitploses contacts 787 to complete a circuit from a 110 A.C.source of potenti-al (FIG. 2) through lamp 263, conductor `264,

Va variable resistance 788 (FIG. 7), contacts 787, wiper 725-5, contacts 783-1 to 783-26, conductors 781-1 to 781-13, and the lamps in the banks 12-1 to 12-4 to ground.

The variable resistance 7 88 may be adjusted to provide the desired amount of light intensity produced by the lamps. The relay 785 has a very low operate and release time. Hence the lamps are energized only for very short intervals between the operation of the magnet M724 and its release. It is preferable that the lamps are not conducting when the wipers of the switch 701 are advanced from one contact to the next. Otherwise contact life Awill be seriously lowered by arcing due to breaking Vthe circuit under load. Hence, the short release time of relay 785 and the short closure time of contacts 747 of the magnet M724 assure breaking of the lamp circuit at relay contact 787 prior to advancement of the wipers 725,-1 to In each of the marking areas 9 and 10, only alternate I banks are energized simultaneously so that each operator will read and mark into the respective keyboardf200-1 or 200-2 the geographic codes of packages located on alternate package centering positions. For example, the

level 790 (FIG. 7) of the master timing switch 701 is;

k,cable 792 to banks 12-5, 12-7, 12-10 and 12-12.

The circnit for energizing the lamps in the banks '12-5 to 12-12 inclusive is similar to that which energizes the banks 12-1 to 12-4. More speciiically the wiper 725-6 of level 790 is connected with the Wiper`725-5, which latter wiper controls the sequential operation of the lamps in the banks `12--1 to 12-4. Hence, the wiper '/2-5-6 will selectively control the operation of the lamps in banks 12-5 to 12-12.

More particularly, the first thirteen contacts 793-1 to 793-1'3 (FIG. 7) of the level 790 are connected to conductors 794-1 to 794-13 of the cable 791. These conductors 794-1 to 794-13 are connected repectively to lamps 831-1 to 831-13 of bank I2-6, lamps 833-1 to 833-13 of bank 12-8, lamps 834-1 to 834-13 of bank 12-9, and lamps 836-1 to 836-13 of bank 12-11. Hence as the wiper 725-6 engages the contacts'793-1 to 793- 13, the lamps in banks 12-6, 12-8, 12-9 and 12-11 will be sequentially energized.

In a similar manner, the lamps in banks 12-5, 12-7,

12-,10 and 12-12 will be sequentially energized by way of conductors 794-14 to 794-26 as the wiper 725-6 engages contacts 793-14 to 793-26. p It will be appreciated that the operation of the lamp banks 12-5 to 12-12 must be synchronized properly with the advancement of the buffer memory readout selector switches by the photosensitive device l5 (FIG. 1). Hence, the photosensitive device 15 must detect a packvage marked by the operator in the area.9 while the second position lamps in the banks 12-6, 12-8, 12-9 and 12-111 are energized. Similarly, the photosensitive device .15 will detect a package handled by the operator in area 10 when the second position lamps in the banks 12-5, l12-7, 12-10 and 12-12 are energized.

Therefore, the photosensitive device ,1-5 may be placed in a position approximately six feet, or a multiple thereof, from the second position lamp in the bank 412-12. However, it will be recalled that, in order to avoid an error when detecting a very small package, it is preferable to have the photosensitive device slightly in advance of the theoretically exact time when a package should be detect-ed, that is, at least when the package centering position of the belt passes the photosensitive device 15. It will also be recalled that the device 15 must also be placed adjacent the forward edge of the yzone in which the first discharge station 11-1 is lo ated.

Routing of a package 7 to the gravity conveyor 17-1A It will be assumed that the package 7 will be handled by the operator in the marking area 9, that the address code 001000 of the distribution board 21,5 is the address code corresponding to the conveyor 17-1A, that the geographical area of the package is V419, that the decoder 600-1A corresponds to the gravity conveyor 17-1A, that the sections 502-1 and 502-2 of the main memory unit 500 received store and advance the first position digit 0 of the address code, that the buffer memory read-in and read-out switches 301 and 302 are in the positions shown, that Vboth keyboards and buier memory units are in use whereby contacts 750 ofA relay 765 are closed, and that the switch contacts '1 and -802 are in their shown closed positions.

An operator in the loading area 8 (FIG. l) will place the package 7 on the belt 3, positioned on a package centering belt position identified by one of the lighted lamps in the banks 12-1 to 12-4. When the package 7 arrives at the marking area 9, a second operator will read the address and will actuate the tens key 4 and the units key 9 of the keyboard 200-1 (iFIG. 2). The second operator will then depress thel enter bar switch 240 to energize the buter memory start relay 30S (FIG. 3). The relay 305 will operate contacts 308 to energize the magnet M|309vof the readfinselector'switch 3.01. The relay 305 will also close contacts` 307 to extend a positive 150 Volt potential through the circuit established by the tens key 4 and the units key 9 of the keyboard 200-1 and by the distribution board 215 to write the address code 001000 into the neon tubes 310.-,.1 to 31.0.-6 of the storage unit 303-1.

The magnet M309 closes vcontacts 3211 to complete a circuit for energizing the release coils 241 to restore the tens key 4 and the units key V9 of .the keyboard 200- 1. Subsequently, the magnet M309 restores to advance the wipers l304-1 to 304-7 to Vthe next accessible contacts in preparation for the entry of the address code of another package.

Meanwhile, the master timing switch 702 (FIG. 7) is being sequentially operated by the clock pulse generator 700 and its amplifier 701 for each three foot movement of the belt 3. Each of the input sections, such as 502-1 (RIG. 5) of the first main memory stage 501-1, Will be marked with a and will remain so marked.

As the package 7 approaches the first discharge staf tion 11-1 it will be detected by the photosensitive device 15. The device 115 will cause the relay 742 (IFIG. 7) to be operated to close contacts 746. This will prepare a circuit for energizing the readout'selector switch'magnet M350 (FIG. 4) of the buffer memory unit 300-1. 'I'he clock pulse generator 700 and its amplifier 7041 will be operating and restoring the magnet M724 of the master timing switch 702 every 36/13 of movement of the belt 3. The wipers 725-1 to 725-6-05 the switch 702 will be `advanced one step for each release of the magnet M724. The first time that the wiper 725-2 engages its second position contacts 735 after the closure of contacts 746, the circuit for operating the readout se.- lector switch magnet M350 is further prepared. When the next clock pulse energizes the magnet M724, the contacts 747 of the magnet `are closed to complete the circuit for energizing the magnet M350.

' The magnet M350 will restore incident to the restoration of the magnet M724 at the end of the clock pulse. The wipers 340-1 to 340-8 of the buffer memory unit 300-1 will be advanced to engage the upper first position contacts V342-1 to 342-8. The neon tubes 3'10-1 to 310-6 are now connected to the input sections, such as 502-1of the main memory input stage 501-1. The section 502-1 is connected to the lower electrode of the neon tube 310-1. The neon tube 310-1 is nonconducting and, therefore, has ground potential at its lower electrode corresponding to a code bit "0. Since the section 502-1 already stores a 0, it will not be affected by the connection to the tube 3110-1. Only the third inl put section -(not shown), which is connected to the conpulses Until the wipers reach the `seventh contact posi-Y tions. At this time, the wiper `7,25-1 engages contacts 736 to prepare a circuit for operating the reset pulse amplifier V34. The next energization of the magnet M724 closes the contacts 755 to apply a pulse to the input V818 `of the resetpulse amplifier 34. The pulse is amplified and .applied to the output 8 17 of the reset `pulse amplifier to reset all of the sections such as 502-1 of the `main memory input stage 01-1. This `would normally Cause the erasure of the code bit v1 from the vthird section (not shown) of the stage 501-1. However, since the tube 3710-3 is ,still conducting and since its lower .elec- .trode is still applied to the input of lsaid third section, 'the 1 willremain marked in .the section.

.Succeeding clock pulses will cause the Wipers 725-1 to '72,5-6 t@ .Continue to advance .until they engage their thirteenth contact positions. Ln `this position, the wipers 725-1 engage the contacts 737. The next succeeding clock pulse Censos the energization of the magnet M724 to again close contacts 755, this time to apply a pulse to the input conductor 757 of the -zone pulse amplifier 00. The amplifier l8,0() applies an amplified output pulse to conductor` 8,16 which is applied to the zone pulse input conductors such as 553 of all of the sections of all of the stages 501-2 to 501-N. This will cause the address code 001000 stored in stage 501-1 to be transferred to the stage 50'1-2.

The wiper 7,25-1 to 725-.6 are then -advanced to the Vfourteenth contact positions. The next energization of magnet M724 closes contacts 7,55 to energize the buffer memory reset relay 840 (FIG. 8). The relay 840 closes contacts V841 to extend ground potential to the upper electrodes of all of the neon tubes 310-1 to 310-6. This will cause the neon tube 310-3 to cease conducting whereby the storage -unit 303-1 ris. reset. However, the input stage 501-1 still retains the address code 001000. This code will be erased when the wipers reached the twentieth accessible contact in which position the wipers 72.5.-1 engages contacts 760. The next energization of the magnet M724 causes the reset pulse amplifier 34 to erase the code from the stage 501-1.

It has been assumed that the code 001000 has been entered into the stage l501-1 and then transferred to the -stage 501-2. It has further been assumed that this particular address code is the code assigned to the decoder 600-1A at transfer mechanism 16-1 and the gravity conveyor 17-1A.

The magnet M724 releases to advance the Wipers 725-1 to 725-6 to their fifteenth contact positions. The wiper 725-4 engages the contact 776 to complete a circuit for applying a negative potential to the synchronizing input conductor 777 .of the decoders 600-.1A and 600-1B (FIG. 6). The conductors 602-1, 602-2, 602-4, 602-5 and 6'02-6 are connected to the 0 conductors, such as 566, of the first, second, fourth, fifth, and sixth sections of stage 501-2. The input conductor 602-3 is connected to the l conductor, such `as '5.67, .of the third section of stage 501-2. Since the stage 501-2 is marked with code 001000, negative potentials now appear at all of the input conductors 602-1 to 602-6. Consequently, a negative Vpotential appears at :the junction 605 and the relay 607 is energized.

The relay 607 energizes the motor start solenoid 609 and the transfer mechanism 16-1 pushes the package 7 from the belt 3 to the gravity conveyor 17-1A. Workmen transfer the package 7 from the gravity conveyor 17-1A to the nearby `car destined for the geographic area represented by the .decimal code 49.

While there has been described what is at present believed to be the preferred embodiment of the invention, it will be understood that various modifications may be ymade therein; and it is .contemplated to cover in the appended claims all such modifications as fallfwithin the true spirit and scope of the invention.

What is claimed is:

l. In a conveyor system of the type in which .objects at a loading position are placed on a moving conveyor at spaced positions for `movement to selected ones .of a plurality of discharge stations adjacent a path traversed by the conveyor and in which control circuits synchro nized with the movement of the conveyor operate transfer mechanisms to remove the objects at their respective selected discharge stations, the combination With the control circuits of a plurality of spaced visually Aobservable devices positioned along the conveyor `at the loading yposition and operated in the order of their appearance in the direction of conveyor vmovement to indicatea-.position lon `the conveyor with respect to which an object is dto l.be positioned. v

2. In a conveyor system of the type in which objects at a loading area are placed on a moving conveyor for movement to selected discharge stations adjacent a path traversed by the conveyor and in which control apparatus automatically removes the objects at their respectiveV discharge stations, the combination with the control apparatus of a plurality of spaced visually observable devices positioned along the conveyor at the loading area and operated in the order of their appearance along the loading area inthe direction of conveyor movement to indicate the positions onA the moving conveyor with respect to which objects are to be positioned.

3. In a conveyor system of the type in which objects at a loading area are placed on a moving conveyor at equally spaced positions for movement to selected ones of a plurality of discharge stations adjacent a path traversed by the conveyor and in which control circuits synchronized with the movement of the conveyor operate transfer mechanisms to remove the objects at their respective selected discharge stations, the combination with the Vcontrol circuits of a plurality of spaced visually observable devices positioned along the conveyor at the loading area, and means operated in synchronism with the movement of the conveyor for operating the devices in the order of their appearance along the loading area in the direction of conveyor movement to indicate the positions on the conveyor with respect to which objects are to be positioned.

4. In a conveyor system of the type in which objects at a loading area are placed on an endless moving conveyor belt at spaced positions for movement to selected ones of a plurality of discharge stations adjacent a path traversed by the belt and in which control circuits synchronized with the movement of the belt operate transfer mechanisms to remove the objects at their respective selected discharge stations, the combination with the control circuits of a plurality of spaced Visually observable devices positioned along the conveyor at the loading area, and means operated in synchronism with the movement of the belt for operating the'devices in the order of their appearance along theloading area in the direction of belt movement to indicate the positions on the moving belt with Vrespect to which objects are to be positioned, whereby stretching of the belt over an extended period of use will not result in inaccurate positioning of the objects.

5. In a conveyor system of the type in which objects at a loading area are placed on an endless moving conveyor belt at equally spaced positions for movement to selected ones of a plurality of discharge stations adjacent a path traversed by the belt and in which control circuits synchronized lwith the movement of the belt operate transfer mechanisms to remove the objects at their respective selected discharge stations, the combination with the control circuits of a plurality Lof lamps positioned along the conveyor belt at the loading area, and means including a timing switch operated in synchronism with the movement of the belt for energizing the lamps in the order of their appearance along the loading area in the direction of belt movement to indicate the positions'of the moving belt with respect to` which objects are to be positioned, whereby stretching of the belt over an extended period of use will not result in' inaccurate positioning of the objects.

A6. In an automatic conveyor system' of the type in which objects are placed on a conveyor for movement to selected discharge stations adjacent the conveyor path and in which a pair of operators in areas along the conveyor write assigned address codes of alternate packages into control apparatus to cause the packages to be selectively removed from the conveyor at their respective dischargefstations, the combination with the control apparatus of at least one group of visually observable devices 'positioned along the conveyor in each area in which an operator is working, each device operated in the order of its appearance in a group in the direction of conveyor movement coincident with the movement of packages which are to be handled by the respective operator past the device. v

7. In an automatic conveyor system of the type in which objects Vare placed on a conveyor for movement to selected discharge stations adjacent the conveyor path and in which a pair of operators in areas along the conveyor write assigned address codes of alternate packages into control apparatus to cause the packages to be selectively Vremoved from the conveyor at their respective discharge stations, the combination with the control apparatus of at least one group of visually observable devices positioned along the conveyor in each area which an operator is working, and circuit means operated in synchronism with the conveyor for operating each device in the order of its appearance in a group in the direction of conveyor movement coincident with the movement of packages which are to be handled by the respective operator past the device.

8. In a conveyor system of the type in which an object intended for delivery to a predetermined ultimate destination is placed on a transporting mechanism for movement to a predetermined one of a plurality of discharge stations adjacent a path traversed by the transporting mechanism, in which control apparatus causes a transfer mechanism to selectively remove the object from the transporting mechanism when it reaches the predetermined discharge station, and in which a manually operable apparatus including a plurality of keys each corresponding to an ultimate object destination causes an address code assigned to the predetermined discharge station to be written into the control apparatus for selectively controlling the transfer mechanism incident to the operation of the key corresponding to the predetermined ultimate destination, the combination with the manually operable apparatus of a plurality of replaceable plug-in circuits each eifective for causing a different address code assigned to a different discharge station to be written into the control apparatus incident to the depression of the key corresponding to the predetermined ultimate destination, whereby the discharge station selected for receiving packages intended for the predetermined ultimate destination may be varied at random.

9. In a mail sorting system of the type in which mail and parcel post packages are placed on a conveyor for movement to selected discharge stations adjacent a path traversed by the conveyor, in which control apparatus cause transfer mechanisms at the discharge stations to selectively remove the packages from the conveyor when they reach their selected discharge stations, and in which manually operable apparatus includes a plurality of keys, each corresponding to a common destination point for a different fixed geographic area, to cause address codes, each of which is assigned to a respective discharge station, to be written into the control apparatus for selectively controlling the transfer mechanisms, in combination with the manually operable apparatus a plurality of replaceable plug-in circuits, each effective to form one of the address codes, mating plug-receiving structure for receiving a selected plug-in circuit for each key, and circuit means including the selected plug-in circuits and the mating structure for causing the respective selected admechanism when they reach their selected discharge stat tions, the combination with the transporting and` transfer mechanisms of control apparatus, comprising a rst and 

